/*
** $Id: lstate.h,v 2.133 2016/12/22 13:08:50 roberto Exp $
** Global State
** See Copyright Notice in lua.h
*/

#ifndef lstate_h
#define lstate_h

#include "lua.h"

#include "lobject.h"
#include "ltm.h"
#include "lzio.h"


/*

** Some notes about garbage-collected objects: All objects in Lua must
** be kept somehow accessible until being freed, so all objects always
** belong to one (and only one) of these lists, using field 'next' of
** the 'CommonHeader' for the link:
**
** 'allgc': all objects not marked for finalization;
** 'finobj': all objects marked for finalization;
** 'tobefnz': all objects ready to be finalized;
** 'fixedgc': all objects that are not to be collected (currently
** only small strings, such as reserved words).

*/


struct lua_longjmp;  /* defined in ldo.c */


/*
** Atomic type (relative to signals) to better ensure that 'lua_sethook'
** is thread safe
*/
#if !defined(l_signalT)
#include <signal.h>
#define l_signalT   sig_atomic_t
#endif


/* extra stack space to handle TM calls and some other extras */
#define EXTRA_STACK   5


#define BASIC_STACK_SIZE        (2*LUA_MINSTACK)


/* kinds of Garbage Collection */
#define KGC_NORMAL  0
#define KGC_EMERGENCY   1   /* gc was forced by an allocation failure */


typedef struct stringtable {
    TString** hash;
    int nuse;  /* number of elements */
    int size;
} stringtable;


/*
** Information about a call.
** When a thread yields, 'func' is adjusted to pretend that the
** top function has only the yielded values in its stack; in that
** case, the actual 'func' value is saved in field 'extra'.
** When a function calls another with a continuation, 'extra' keeps
** the function index so that, in case of errors, the continuation
** function can be called with the correct top.
*/
typedef struct CallInfo {
    StkId func;  /* function index in the stack */
    StkId top;  /* top for this function */
    struct CallInfo* previous, *next;  /* dynamic call link */
    union {
        struct {  /* only for Lua functions */
            StkId base;  /* base for this function */
            const Instruction* savedpc;
        } l;
        struct {  /* only for C functions */
            lua_KFunction k;  /* continuation in case of yields */
            ptrdiff_t old_errfunc;
            lua_KContext ctx;  /* context info. in case of yields */
        } c;
    } u;
    ptrdiff_t extra;
    short nresults;  /* expected number of results from this function */
    unsigned short callstatus;
} CallInfo;


/*
** Bits in CallInfo status
*/
#define CIST_OAH    (1<<0)  /* original value of 'allowhook' */
#define CIST_LUA    (1<<1)  /* call is running a Lua function */
#define CIST_HOOKED (1<<2)  /* call is running a debug hook */
#define CIST_FRESH  (1<<3)  /* call is running on a fresh invocation
                                   of luaV_execute */
#define CIST_YPCALL (1<<4)  /* call is a yieldable protected call */
#define CIST_TAIL   (1<<5)  /* call was tail called */
#define CIST_HOOKYIELD  (1<<6)  /* last hook called yielded */
#define CIST_LEQ    (1<<7)  /* using __lt for __le */
#define CIST_FIN    (1<<8)  /* call is running a finalizer */

#define isLua(ci)   ((ci)->callstatus & CIST_LUA)

/* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */
#define setoah(st,v)    ((st) = ((st) & ~CIST_OAH) | (v))
#define getoah(st)  ((st) & CIST_OAH)


/*
** 'global state', shared by all threads of this state
*/
typedef struct global_State {
    lua_Alloc frealloc;  /* function to reallocate memory */
    void* ud;         /* auxiliary data to 'frealloc' */
    l_mem totalbytes;  /* number of bytes currently allocated - GCdebt */
    l_mem GCdebt;  /* bytes allocated not yet compensated by the collector */
    lu_mem GCmemtrav;  /* memory traversed by the GC */
    lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
    stringtable strt;  /* hash table for strings */
    TValue l_registry;
    unsigned int seed;  /* randomized seed for hashes */
    lu_byte currentwhite;
    lu_byte gcstate;  /* state of garbage collector */
    lu_byte gckind;  /* kind of GC running */
    lu_byte gcrunning;  /* true if GC is running */
    GCObject* allgc;  /* list of all collectable objects */
    GCObject** sweepgc;  /* current position of sweep in list */
    GCObject* finobj;  /* list of collectable objects with finalizers */
    GCObject* gray;  /* list of gray objects */
    GCObject* grayagain;  /* list of objects to be traversed atomically */
    GCObject* weak;  /* list of tables with weak values */
    GCObject* ephemeron;  /* list of ephemeron tables (weak keys) */
    GCObject* allweak;  /* list of all-weak tables */
    GCObject* tobefnz;  /* list of userdata to be GC */
    GCObject* fixedgc;  /* list of objects not to be collected */
    struct lua_State* twups;  /* list of threads with open upvalues */
    unsigned int gcfinnum;  /* number of finalizers to call in each GC step */
    int gcpause;  /* size of pause between successive GCs */
    int gcstepmul;  /* GC 'granularity' */
    lua_CFunction panic;  /* to be called in unprotected errors */
    struct lua_State* mainthread;
    const lua_Number* version;  /* pointer to version number */
    TString* memerrmsg;  /* memory-error message */
    TString* tmname[TM_N];  /* array with tag-method names */
    struct Table* mt[LUA_NUMTAGS];  /* metatables for basic types */
    TString* strcache[STRCACHE_N][STRCACHE_M];  /* cache for strings in API */
} global_State;


/*
** 'per thread' state
*/
struct lua_State {
    CommonHeader;
    unsigned short nci;  /* number of items in 'ci' list */
    lu_byte status;
    StkId top;  /* first free slot in the stack */
    global_State* l_G;
    CallInfo* ci;  /* call info for current function */
    const Instruction* oldpc;  /* last pc traced */
    StkId stack_last;  /* last free slot in the stack */
    StkId stack;  /* stack base */
    UpVal* openupval;  /* list of open upvalues in this stack */
    GCObject* gclist;
    struct lua_State* twups;  /* list of threads with open upvalues */
    struct lua_longjmp* errorJmp;  /* current error recover point */
    CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */
    volatile lua_Hook hook;
    ptrdiff_t errfunc;  /* current error handling function (stack index) */
    int stacksize;
    int basehookcount;
    int hookcount;
    unsigned short nny;  /* number of non-yieldable calls in stack */
    unsigned short nCcalls;  /* number of nested C calls */
    l_signalT hookmask;
    lu_byte allowhook;
};


#define G(L)    (L->l_G)


/*
** Union of all collectable objects (only for conversions)
*/
union GCUnion {
    GCObject gc;  /* common header */
    struct TString ts;
    struct Udata u;
    union Closure cl;
    struct Table h;
    struct Proto p;
    struct lua_State th;  /* thread */
};


#define cast_u(o)   cast(union GCUnion *, (o))

/* macros to convert a GCObject into a specific value */
#define gco2ts(o)  \
    check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts))
#define gco2u(o)  check_exp((o)->tt == LUA_TUSERDATA, &((cast_u(o))->u))
#define gco2lcl(o)  check_exp((o)->tt == LUA_TLCL, &((cast_u(o))->cl.l))
#define gco2ccl(o)  check_exp((o)->tt == LUA_TCCL, &((cast_u(o))->cl.c))
#define gco2cl(o)  \
    check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl))
#define gco2t(o)  check_exp((o)->tt == LUA_TTABLE, &((cast_u(o))->h))
#define gco2p(o)  check_exp((o)->tt == LUA_TPROTO, &((cast_u(o))->p))
#define gco2th(o)  check_exp((o)->tt == LUA_TTHREAD, &((cast_u(o))->th))


/* macro to convert a Lua object into a GCObject */
#define obj2gco(v) \
    check_exp(novariant((v)->tt) < LUA_TDEADKEY, (&(cast_u(v)->gc)))


/* actual number of total bytes allocated */
#define gettotalbytes(g)    cast(lu_mem, (g)->totalbytes + (g)->GCdebt)

LUAI_FUNC void luaE_setdebt( global_State* g, l_mem debt );
LUAI_FUNC void luaE_freethread( lua_State* L, lua_State* L1 );
LUAI_FUNC CallInfo* luaE_extendCI( lua_State* L );
LUAI_FUNC void luaE_freeCI( lua_State* L );
LUAI_FUNC void luaE_shrinkCI( lua_State* L );


#endif

